Refer to FIG. 1 for a conventional blue light LED structure. In the conventional blue light LED structure, an N-type GaN (gallium nitride) layer 2, an activation layer 3 and a P-type GaN layer 4 are sequentially formed on a sapphire substrate 1. Then, an N-type electrode 5 and a P-type electrode 6 are respectively coated on the N-type GaN layer 2 and the P-type GaN layer 4. Thus is formed an LED structure.
There is intrinsic lattice mismatch between the sapphire substrate 1 and the N-type GaN layer 2/the P-type GaN layer 4. Thus, the N-type GaN layer 2 formed on the sapphire substrate 1 during an epitaxial process has a high-defect density. Thus the photoelectric performance of an LED component is degraded, the photoelectric efficiency is reduced and lifespan is shortened.